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Thermal conductivity and viscosity of self-assembled alcohol/polyalphaolefin nanoemulsion fluids.

Xu J, Yang B, Hammouda B - Nanoscale Res Lett (2011)

Bottom Line: Very large thermal conductivity enhancement had been reported earlier in colloidal suspensions of solid nanoparticles (i.e., nanofluids) and more recently also in oil-in-water emulsions.In this study, nanoemulsions of alcohol and polyalphaolefin (PAO) are spontaneously generated by self-assembly, and their thermal conductivity and viscosity are investigated experimentally.Both thermal conductivity and dynamic viscosity of the fluids are found to increase with alcohol droplet loading, as expected from classical theories.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA. baoyang@umd.edu.

ABSTRACT
Very large thermal conductivity enhancement had been reported earlier in colloidal suspensions of solid nanoparticles (i.e., nanofluids) and more recently also in oil-in-water emulsions. In this study, nanoemulsions of alcohol and polyalphaolefin (PAO) are spontaneously generated by self-assembly, and their thermal conductivity and viscosity are investigated experimentally. Alcohol and PAO have similar thermal conductivity values, so that the abnormal effects, such as particle Brownian motion, on thermal transport could be deducted in these alcohol/PAO nanoemulsion fluids. Small angle neutron-scattering measurement shows that the alcohol droplets are spheres of 0.8-nm radius in these nanoemulsion fluids. Both thermal conductivity and dynamic viscosity of the fluids are found to increase with alcohol droplet loading, as expected from classical theories. However, the measured conductivity increase is very moderate, e.g., a 2.3% increase for 9 vol%, in these fluids. This suggests that no anomalous enhancement of thermal conductivity is observed in the alcohol/PAO nanoemulsion fluids tested in this study.

No MeSH data available.


Relative thermal conductivity of the alcohol/PAO nanoemulsion fluids versus alcohol volumetric fraction. The prediction by the Maxwell equation is shown for comparison.
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Figure 3: Relative thermal conductivity of the alcohol/PAO nanoemulsion fluids versus alcohol volumetric fraction. The prediction by the Maxwell equation is shown for comparison.

Mentions: Figure 3 shows the relative thermal conductivity as a function of the loading of alcohol nanodroplets in alcohol/PAO nanoemulsion fluids at room temperature. The prediction by the Maxwell model is also plotted in Figure 3 for comparison. The relative thermal conductivity is defined as keff/ko, where ko and keff are the thermal conductivities of the base and nanoemulsion fluids, respectively. The PAO thermal conductivity is experimentally found to be 0.143 W/m K at room temperature, which compares well with the literature value [32]. It can be seen in this figure that the relative thermal conductivity of the alcohol/PAO nanoemulsion fluids appears to be linear with the loading of alcohol nanodroplets over the range from 0 to 9 vol%. However, the magnitude of the conductivity increase is rather moderate in the fluids, e.g., a 2.3% increase for 9 vol% loading.


Thermal conductivity and viscosity of self-assembled alcohol/polyalphaolefin nanoemulsion fluids.

Xu J, Yang B, Hammouda B - Nanoscale Res Lett (2011)

Relative thermal conductivity of the alcohol/PAO nanoemulsion fluids versus alcohol volumetric fraction. The prediction by the Maxwell equation is shown for comparison.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211338&req=5

Figure 3: Relative thermal conductivity of the alcohol/PAO nanoemulsion fluids versus alcohol volumetric fraction. The prediction by the Maxwell equation is shown for comparison.
Mentions: Figure 3 shows the relative thermal conductivity as a function of the loading of alcohol nanodroplets in alcohol/PAO nanoemulsion fluids at room temperature. The prediction by the Maxwell model is also plotted in Figure 3 for comparison. The relative thermal conductivity is defined as keff/ko, where ko and keff are the thermal conductivities of the base and nanoemulsion fluids, respectively. The PAO thermal conductivity is experimentally found to be 0.143 W/m K at room temperature, which compares well with the literature value [32]. It can be seen in this figure that the relative thermal conductivity of the alcohol/PAO nanoemulsion fluids appears to be linear with the loading of alcohol nanodroplets over the range from 0 to 9 vol%. However, the magnitude of the conductivity increase is rather moderate in the fluids, e.g., a 2.3% increase for 9 vol% loading.

Bottom Line: Very large thermal conductivity enhancement had been reported earlier in colloidal suspensions of solid nanoparticles (i.e., nanofluids) and more recently also in oil-in-water emulsions.In this study, nanoemulsions of alcohol and polyalphaolefin (PAO) are spontaneously generated by self-assembly, and their thermal conductivity and viscosity are investigated experimentally.Both thermal conductivity and dynamic viscosity of the fluids are found to increase with alcohol droplet loading, as expected from classical theories.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA. baoyang@umd.edu.

ABSTRACT
Very large thermal conductivity enhancement had been reported earlier in colloidal suspensions of solid nanoparticles (i.e., nanofluids) and more recently also in oil-in-water emulsions. In this study, nanoemulsions of alcohol and polyalphaolefin (PAO) are spontaneously generated by self-assembly, and their thermal conductivity and viscosity are investigated experimentally. Alcohol and PAO have similar thermal conductivity values, so that the abnormal effects, such as particle Brownian motion, on thermal transport could be deducted in these alcohol/PAO nanoemulsion fluids. Small angle neutron-scattering measurement shows that the alcohol droplets are spheres of 0.8-nm radius in these nanoemulsion fluids. Both thermal conductivity and dynamic viscosity of the fluids are found to increase with alcohol droplet loading, as expected from classical theories. However, the measured conductivity increase is very moderate, e.g., a 2.3% increase for 9 vol%, in these fluids. This suggests that no anomalous enhancement of thermal conductivity is observed in the alcohol/PAO nanoemulsion fluids tested in this study.

No MeSH data available.